The present invention provides a two-stage melt polymerization process for the production of high molecular weight polybenzimidazoles utilizing certain dicarboxylic compounds as monomers.
Ward U.S. Pat. No. 4,672,104 teaches a two step process for the production of polybenzimidazoles. This two-stage melt polycondensation process has been found to operate with significant variations in product thermal history due reactor design, yielding a product heterogeneous in IV, solubility, solution filtration quality, color, etc. Thus, efforts were initiated to optimize and improve the second stage SSP (solid-state polymerization) reaction equipment and process conditions.
Ward U.S. Pat. No. 4,717,764 teaches a two step process for the production of benzimidazoles/aromatic amide polymers and copolymers and wholly aromatic polyamides.